Thanks for the info Chris. I’ll take note of it and make time to play with mine this weekend and see where they are. I’m really hoping the error correction is the missing piece. I’ve got my Controlled Acceleration turned way up as well and it only moderately helps.
I think I have it tuned out. I started with error correction. My mistake, the controller was set at 32. I rolled it back to 10 and my dash started flashing all sorts of numbers 144…10…144, so I set it at 11 and it cleared up the strange numbers.
Next I started with controlled acceleration. Previous setting was 18, dropped it to 12 then 10 and the stuttering was happening at a lower and lower speed. Bumped it up to 30 and it was almost gone. At 35 the stutter was completely gone.
Is there any reason I shouldn’t go that high on the controlled acceleration?
Not if performance is where you want it.
Good job, I know what’s involved in tuning. Try this try that, then try both. After an hour, I give up.
Are you programming on line now with the programming port added to Gem?
Try monitor function and give me a plug. I don’t know why everyone doesn’t use it for trouble shooting. Shows much more than you would expect. Switch and throttle position etc. You can even graph, I believe 3 parameters. Such as A amps versus field current.
Controller temperature. Almost forgot that, some are struggling to keep cool.
I hope this info helps others. It took me about 15 trips around my block to tune it out.
Programming on line. No problem hooking up your usb harness. Pin 16 was open on the plug (originally a T1) which is the neg for the tach according to the GL2 Tech, worked like a charm.
I need to relocate the usb so I can get to it easier and strap my laptop down for driving. Once I do that Ill get some real time data.
If anyone needs this setup, I highly reccomend Inwo’s cable. Couldnt have been any easier.
Extend the 3 wire plug. That’s why it’s built that way. I use a 25’ MF extension wire.
If everyone wanted this, I could make them long enough to reach passenger area.
I suppose Bluetooth would work to.
Ooohhhhh…Bluetooth
I can’t live with the performance of that setting. Anything above 15 is too much lag for me. I also believe that delaying acceleration is masking the root issue which feels to me to be an oscillation between other trip points. I think that on hard acceleration the field and armature currents are reaching their maxes and clamping down or shifting ratios. It’s happening so fast and extreme that it is causing an oscillation in those parameters. I wish I had the engineering docs for both motors to reference the various curves. I’m pretty sure the answer lies in there somewhere.
I’m going to try to play with it this weekend if I can get out of building a fence for my daughter (wife sprung that on me last night).
As far as running the diagnostics, I’ve tried that but when my laptop is connected during use, it affects the controller function and it behaves differently and the display flashes all kinds of weird numbers. I think its pulling down the control voltage on the processor, but not sure.
I’m glad you’ve found a workable solution for your application. Its both fun and frustrating to mod these things. I just wish I had more time right now.
Well I thought I had the solution. Acceleration did suffer a small amount but once voltage dropped some, same stutter at the same speeds. One thing I did notice is if I hold my foot down on the brake while the car is stuttering, like power breaking, it seems to push the car out of the stutter.
Please let me know what you come up with!
That’s an interesting observation. It seems to go against the grain of what I thought I was observing as I thought it was decreasing as the car gained speed but what you observed suggests that increased speed is a component of the phenomena. Hmmmm??? Mine seems to do it more when the car is heavily loaded which would seem to be similar to riding the brake. I’m supposed to be cooking right now but I might go hook the laptop to it and see what I find. I still think its a component of hte knee point tuning which I only understand at the very high level but may have to dig in deeper on it.
What’s for dinner @Mr.Vern?
Its a dish my father who is a retired chef used to serve at his restaurant that everybody loved. He called it Chicken a la Suisse. It’s a white wine and shallots based sauce over chicken. Everyone always asked for hte recipe and he never really wrote it down so I took a shot at it from memory today. Letting it rest right now so we’ll see how it came out.
I did just connect my laptop to the car and printed the current settings. I’m going to study them for a minute while that food cools and then I’ll formulate a plan of attack on the food and then the car. I’ll keep you posted.
Any luck @Mr.Vern? I’m going to wipe the slate clean and start over tomorrow.
No luck yet. I just played with it and broke it worse so I reloaded all of my original settings and started over but my batteries were at 50% (84V) so I decided to stop and charge them so I am working from a baseline of full charge (96V). I did find that error compensation seemed to have an effect when I ran it up to 55. I also found that on take off I’m drawing >450A which I think is way too much for the controller to withstand. I think some protection is kicking in. I’ve also got my field weakening start at 50 where your’s is at 35. I thought that was determined by RPM but it looks like the only thing that would explain why mine oscilates at start up under load and yours does it at midrange. I’m still confused. I also had my car full of good eaters yesterday and discovered that load absolutely affects how much mine does it. I’ll try to play again Sunday with the car charged fully.
Very funny, car full of good eaters. Does that mean that the stuttering was worse? Im in the process of cleaning out my garage, too many projects and need to clean up some stuff. But I should be back at it tomorrow night.
OK, played around tonight. No matter what changed I still have the stutter. De-accelerating from anywhere above the 20mph mark, coasting down to about 12-17mph, from there, hitting the accelerator gives me the stutter. It will surge until I am over 20mph again. I ran the GE Sentry Monitor and while it was stuttering and the motor amps were surging up and down, off the page even.
I got so fed up I plugged in the RF4 settings I had and the stutter was still there but much less. I charge my 28s LifePO4 batteries to 3.5v, once they settle out they are at 92.7v. At 91.7v, the stutter is gone all together. Are we just pushing the limits of the controller? What I find interesting is 13/16/18 which are spares have values. I wonder if they mean something?
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Yes, more load equals more stutter. I’m trying to get back to this but literally have every minute booked til Friday night (don’t tell my wife or she’ll fill it). My current theory is that the internal resistance of the R4F motor is lower than stock so the extra voltage is running the current way up and causing a self protection circuit to clamp it off and then it turns back on and oscillates. Try running #4 Current Limit down to 200 or so and see if the problem diminishes. Overall torque might suffer but that will test my theory. I wish I had time to do it myself.
I’ll give that a try tonight. Installing one of @Inwo’s usb’s Has been a lifesaver. Bluetooth is next.
No luck dropping current limit to 200. Still surging like crazy with a high charge. You can hear the motor surging and slamming the the gears.
Weird I have a 2002 Ford Think with a 7.5 D&D (R4F) motor and I’m running 96 volts with no problems. The Ford Think uses a GE controller which is very similar to the Gem. Strange that the Gem’s have a problem but the Think doesn’t. I tried changing all the settings to match yours just to see if I could reproduce your problem but it ran great. I would think the motors are the same other than the way they mount. You could contact D&D and ask if there is actually a difference other than the mounting
See if you can get enough performance from turf mode. Grant has been running in turf with no changes to settings. Might be able to beef up speed over stock settings.